In video coding systems, a conventional encoder may code a source video sequence into a coded representation that has a smaller bit rate than does the source video and, thereby achieve data compression. A decoder may then invert the coding processes performed by the encoder to retrieve the source video.
Modern block-based encoders tessellate spatial regions into non-overlapping coding units which are encoded atomically albeit they are coded in relation to neighboring coding units. This scheme presents several issues. First, for large coherent regions, block-based encoders incur signaling per coding unit, and rely on entropy coding (usually performed in some form of raster-scan ordering of the coding units) to reduce signaling overhead. Additionally, for bit streams that exhibit temporal correlation over a large spatial region, there is a computational overhead incurred by the encoders/decoders as they process one coding unit at a time. Thus, block-based encoders can lose some of the efficiencies that otherwise can be achieved when coding large temporally-correlated image information.
The inventors perceive a need in the art for a block-based coding protocol that permits efficient coding of temporally-correlated image information in source video.